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AR# 22014

LogiCORE FIFO Generator - Does not allow you to select full width of data count

Description

When using FIFO Generator Core, the allowed data count width is less than it should be.

For example:

If you select the FIFO depth to be 16, you will need 5-bits to represent the full span of data count. However, the allowed data count width is only 1 to 4. You are not able to select 5 for the data count width.

Solution

If you concatenate FULL flag with DATA_COUNT, you will get a counter that spans the entire range that you need. The DATA_COUNT bits will count the number of words in the FIFO. However, when it is FULL or EMPTY, the DATA_COUNT value will be all 0s. Therefore, you need a way to differentiate between FULL and EMPTY. You can use the FULL flag for this purpose.

AR# 22014
Date Created 09/04/2007
Last Updated 12/15/2012
Status Active
Type General Article